1. Field of the Invention
The present invention relates to woven fabric that has been treated for water or stain repellency, and in particular, to hems, edges, patches and seams for such fabrics, and to methods of making the same.
2. Description of the Related Art
State-of-the-art woven fabrics used for outdoor clothing and other articles are commonly treated to make the fabric water and/or stain repellent (collectively referred to herein as “water repellent”). For example, some fabrics are impregnated with a silicone resin. Water repellent woven fabrics have clear advantages. At the same time, however, fabrics treated for water repellency have a number of disadvantages. Most notably, water repellent finishes, while advantageously repelling water, also repel liquid adhesives, whether they be liquid at ambient temperature or melted at elevated temperatures. As a result, it has become an important challenge in the outdoor fabric industry to find a means for affixing patches, seam-sealing tapes and other materials to the external surface of water repellent woven fabric.
Water repellent articles generally fall into two categories: articles having a waterproof external layer, and articles having a vapor permeable membrane covered with a woven, water repellent fabric. The first group, which generally comprises rain slickers, ponchos and similar articles, uses a monolithic external layer, such as PVC, which is inherently waterproof. Because the outer layer is monolithic in nature and because the material can typically be welded, as opposed to sewn, such articles can be truly waterproof. For the same reasons, however, such articles can be heavy and can become stiff in cold weather. In addition, such articles do not allow water vapor to escape from within the article, and thus can cause discomfort due to internal condensation.
The second group of articles, such as the now famous GORE-TEX fabric, combines a waterproof but breathable internal membrane with a water repellent external woven fabric. The internal membrane allows water vapor to pass through, such as when an individual is exercising in a jacket and the moisture content inside the jacket increases. Water vapor exits through the membrane to reduce or prevent condensation on the inside of the jacket, which can maintain the individual drier and warmer. The external layer of woven fabric protects the internal layer from physical damage and helps prevent the membrane from being saturated. If the exterior surface of the membrane is saturated with water, the water itself inhibits vapor from passing through the membrane. Accordingly, it can be very important to keep the external surface of the membrane dry. Thus, the external, water repellent fabric helps prevent water from passing therethrough and being trapped against the membrane. In addition, the woven fabric resists tearing, such as when a branch or other article rubs across the material. In combination, the layers of fabric resist abrasion damage and prevent water from passing into the article, while at the same time allowing water vapor to exit the article.
Because the industry has failed to develop an adhesive that can bond with the exterior surface of water repellent woven fabrics and provide a strong, soft, lightweight and durable bond to a wide variety of textiles, all of the articles in this second group have generally required stitching, such as at the edges of the fabric, at the seams, where zippers or other articles attach to the fabric, or at the pockets. But more importantly, to prevent fraying at the edges of such fabric, the industry typically folds the edge over itself and stitches the fold. Stitching can create numerous leaks in an otherwise waterproof article, each hole allowing water to migrate through all layers of the material. Even where adhesives have been used, such as that illustrated in U.S. Pat. No. 4,604,152 to Liukko, it has still been necessary to stitch the edge of the fabric to prevent fraying. In the few cases when raw edges have been left present, a strong fraying potential remains that severely limits choices of fabrics or the cosmetically acceptable life of the garment.
To solve problems associated with stitching, the industry has developed tapes for application to the interior of the seams. The use of interior seam-sealing tape can be tedious and expensive, however, as the type of tape and adhesive must be carefully matched with the particular interior surface material, and the time, temperature and pressure associated with applying such tapes must be carefully controlled. In addition, such multi-layered, taped seams in conjunction with the turned back seam allowance add significant weight, stiffness, and cost to the resultant article. As many of these articles are used for athletic and competitive outdoor purposes, an increase in the weight and stiffness of the article is undesirable.
In addition, because the weight and bulk of such articles continue to be reduced for functionality purposes, such articles with reduced amounts of surface fiber in their top layers now are even more susceptible to damage from abrasion or other wear.